SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '393953f4b91216eb020355de6ac62e9f048c852d80fe0d648fc4a52afc79d164' 
  AND token = 'eJKSEuw4hp0mhWPPUsGjsWbhFZoKUOfSFeYjDKL5dzY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}